Puberty Sexual Education For Boys And Girls -1991- English.46 -

Shoulders broaden, and muscle mass increases.

: It examines the role of the pituitary gland in signaling the ovaries to produce estrogen and the testicles to produce testosterone. Shoulders broaden, and muscle mass increases

While the average age for girls is 8–13 and for boys is 9–14, everyone is different. There is no "right" time to start. Shoulders broaden, and muscle mass increases